AP Stat Review

Descriptive Statistics

Experimental Design

Probability Inferential

Statistics

Conditions

Grab Bag

100 points

If the mean of a distribution is greater than its median, what is

most likely the shape of the distribution?

Skewed right

200 points

If the range of a set of data is 36, what is a reasonable estimate of the standard

deviation?6

300 points

72.4

If the test scores of a class of 30 students have a mean of 75.6 and the test scores of another class of 24 students have a mean of 68.4, then the mean of the combined group is…

400 pointsJoey scored a 720 on the math portion of the SAT and Luke

scored a 34 on the math portion of the ACT. Scores for each test are

Normally distributed. The SAT has a mean of 580 and a standard deviation of 100, while the ACT

has a mean of 26 with a standard deviation of 5. Who had the better

relative performance? Luke

500 points

• For a particular bivariate data set, r2 is found to be 0.64. Interpret this value.

64% of the variation in y can be accounted for by least squares regression

of y on x.

100 points

When do we say that the design of a study is biased?

When certain outcomes are systematically favored.

200 points

What is the difference between an observational study and an experiment?

In an experiment, a treatment is applied.

300 points

A research team wishes to compare performance in AP

Statistics based on whether the students were taught using activity-based or traditional

lecture methods. The final grades in AP Statistics for 500 students

were collected. What is the population of interest?All students taking AP Statistics

400 points

Name four components for a valid controlled experiment.

Control, comparison, replication, and randomization

500 points

What is the purpose of a control group in an experiment?

To control the effect of lurking variables and to reduce bias

100 pointsA company claims that the number of defective items manufactured during

each run of making 100 of their products is independent of the number from other runs and that the proportion

of defectives is no more than 4%. Assume that the proportion of

defectives for each run is .04. What is the probability that there will be no

defectives on the next run?0.017

200 pointsThe number of sweatshirts a vendor sells

daily has the following probability distribution:

If each sweatshirt sells for $25, what is the expected daily total dollar amount taken in by

the vendor from the sale of sweatshirts?

$38

X 0 1 2 3 4 5

P(X) 0.3 0.2 0.3 0.1 0.08 0.02

300 points

In a certain game, a fair die is rolled and a player gains 20 points if the die

shows a “6.” If the die does not show a “6,” the player loses 3 points. If the die

were to be rolled 100 times, what would be the expected total gain or loss

for the player?About 83

400 pointsAll bags entering a research facility are screened.

Ninety-seven percent of the bags that contain forbidden material trigger an alarm. Fifteen

percent of the bags that do not contain forbidden material also trigger the alarm. If 1 out of every

1,000 bags entering the building contains forbidden material, what is the probability that a bag that triggers the alarm will actually contain

forbidden material?

0.00643

500 points

A student is taking a 5 question multiple choice test. Each question has

4 choices of answers. If a student randomly answers the questions find

the probability that the student answers at least 4 questions correctly.

0.015625

100 points

A P-value of a test of significance is the probability that…

A sample of this size will produce a

statistic this or more extreme if the null hypothesis is true.

200 points

Correct this statement: if the P-value of a test is greater than α, we

accept the null hypothesis.

We fail to reject the hull hypothesis

300 points

What is a type I error?

We reject the null hypothesis when we should

not have.

400 points

Name two way we can reduce the width of a confidence interval?

Increase sample size; reduce the confidence

level

500 points

A local news station reports that the 97% confidence interval for a

candidate’s support was (43%, 48%). What does the phrase 97%

confidence mean?If we repeated this procedure many times, 97% of the resulting CI’s would contain the

true population proportion.

100 points

List the conditions for a one-sample z-test.

SRS; Normality; Independence; σ is

known.

200 points

Name the conditions for a one-proportion z-test.

SRS;

np ≥ 10 and n(1 – p) ≥ 10;

population > 10*sample

300 points

Name the conditions for Chi-square GOF test.

SRS;

All expected counts ≥ 1; No more than 20% of expected counts < 5

400 points

How do we show Normality for a t-test?

Stated; n > 30 (CLT); n > 15 with no clear outliers (CLT); n < 15 with no

skewness or outliers (CLT)

500 points

What do we say if a condition is not met?

Continue with the test, but we have concerns over the results.

100 points

What is z* for a 95% confidence interval?

1.96

200 pointsWhat is t* for a 90% confidence interval for a

sample size of 30?

1.7011

300 pointsA large company is considering opening a franchise in St. Louis and wants to estimate the mean household income for the area using a simple random sample of households. Based on information from a pilot study, the company assumes that the standard deviation of household incomes is σ = $7,200. Of the following, which is the least number of households that should be surveyed to obtain an estimate that is within $200 of the true mean household income with 95% confidence?

About 5000 (4978)

400 points

Name two ways of increasing the power of a test.

Increase sample size, increase alpha,

decrease standard deviation

500 points

How can we tell if a residual plot reveals a linear pattern?

Random scatter, no patterns